I. Field of the Invention
The present invention relates generally to the field of concrete and cement and more particularly to a method of reducing and eliminating voids in finished cement products by the addition of activated carbon which results in a hydrophobic concrete composition with reduced voids.
II. Description of the Related Art
Voids are formed in concrete and cement structures as the structure is prepared, due to dehydration, typically during the mixing process. Voids are typically air spaces that can ultimately be occupied by moisture creating localized failure points in concrete. The void formation results in moisture retention in the structures and further moisture uptake by the resulting porous structure. Inherent moisture in cement causes loss of structural integrity in finished concrete as well as undermining the adhesion of finished concrete. Sometimes, occluded air in the cement is driven off to collapse pore volume during mixing. One attempt at addressing moisture retention in cement is the formation of Macro-Defect-Free (MDF) cement. These improved cement formulations, also called organo-cement composites, contain specific polymers are typically used as a patching compound where adhesion and durability are important performance factors. It has been determined that while the polymer content of these formulations plays a role in the increased strength of the cement, detrimental moisture ingress is also promoted. Resultant plasticization is a major cause of the loss of mechanical strength in finished concrete. Therefore, although the MDF cement can be strong in terms of its load bearing capacity, the formation of voids in the initial mixing and the retention and ingress of moisture remain a problem in the structure due to crack formation.
In general, the invention features a method of using activated carbon in cement mixtures, which can include vinyl polymers. The method and resulting composition can reduce or eliminate moisture retention and moisture uptake in finished cement products. The invention also features a general characterization method of the resulting composition. Use of activated carbon powder in a cement formulation has been determined to result in effectively eliminating the problem of moisture retention due to void formation during mixing and atmospheric moisture uptake. The finished cement product is hydrophobic.
In general, in one aspect, the invention features a composition, including a cement mixture and activated carbon, wherein the cement and activated carbon are mixed together in water.
In one implementation, the activated carbon is added to comprise a weigh percentage of the mass of the dry cement.
In another implementation, the activated carbon constitutes 10% of the total mass of the dry cement.
In another implementation, the activated carbon constitutes 25% of the total mass of the dry cement.
In another implementation, the activated carbon constitutes 50% of the total mass of the dry cement.
In another implementation, a commercially available cement can be used.
In another implementation, a cement composition of crushed limestone, silica, iron and aluminum can be used.
In another implementation, the cement further comprises a vinyl polymer.
In another aspect, the invention features a finished concrete composition, including a hardened cement mixture, the mixture including vinyl polymers and activated carbon, the composition having a plurality of filled voids, the voids being filled with activated carbon having interacted with the vinyl polymers.
In one implementation, the voids are filled with an adduct formed by the interaction of the activated carbon and the vinyl polymers.
In another aspect, the invention features a method of manufacturing concrete having reduced voids, including mixing a portion of cement, silica, a vinyl polymer and activated carbon in water, wherein the activated carbon is a weight percentage of the total mass of the cement.
In one implementation, the mixture is mixed to a pasty consistency.
In another implementation, the mixture is allowed to stand for a period of time.
In another implementation, the mixture is heat treated to form solid concrete.
In still another aspect, the invention features a cement composition, including a cement formulation including vinyl polymers and activated carbon wherein valence electrons of the carbon are in chemical interaction with xcfx80-electron of double bonds of the vinyl polymers.
In yet another aspect, the invention features a composition, including a cement mixture containing limestone, silica and vinyl polymers. The vinyl polymers are dispersed throughout the cement mixture along with activated carbon capable of reacting with the double bonds of the vinyl polymer to form an adduct in voids that are inherent in the cement mixture when the cement mixture has solidified.
One advantage of the invention is that moisture content is reduced or eliminated in finished cement products.
Another advantage of the invention is that voids are reduced or eliminated in finished cement products.
Other objects, advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention.